Ringbom Stirling video

[mklotz]

A friend back East has been pestering me to show him how a Ringbom Stirling works. I finally got around to making a video and, knowing how this tribe of codgers loves videos, am passing it along for your enjoyment.

[ame]http://www.youtube.com/watch?v=RcHAnVB-knE[/ame]

Noisy little devil, isn't it? Not as bad as one of those infernal ICs but, still, noisy for a Stirling.

The engine is my interpretation of Jerry Howell's plans. It uses a graphite power piston running in an aluminum cylinder. The aluminum displacer runs in a graphite bearing. As with all Ringboms, there is no mechanical connection between the displacer and the rest of the engine. The displacer is driven solely by the pressure fluctuations within the engine.
It's arguably the simplest mechanical Stirling design. (Water piston Stirlings are simpler but they aren't mechanical.)

The cold end of the displacer chamber has a water jacket. A tiny pump, driven by a low-tech rubber band pumps water from the cooling tower through the jacket. The pump is interesting. It's an oscillator engine run backwards. The stainless piston is driven by the pulley. It is encased in a pivoting graphite cylinder that alternately covers and uncovers the inlet and outlet as it rotates.

 

[putputman]

Marv, normally stirling engines are noted for not having any power. Yours sounds like it has a ton of power.

I have yet to build a stirling engine of any kind. They are in the bucket list, but somewhere in the middle. That one just might move it up towards the top.

 

[mklotz]

"Ton of power" and "Stirling" in the same sentence borders on the oxymoronic. It manages to overcome its internal friction, the friction and back pressure of the pump and still compress a lot of air into noise but that's about it.

Any Stirling will have more power if you put a water jacket on it. Power output is directly proportional to the temperature differential between hot and cold end so anything one can do to cool the cold end will show up immediately in performance. Water jackets are especially effective.

 

[Deanofid]

It runs very well, Marv. Nice water pump setup, too.
Yes, they're kind of noisy. I've heard them referred to as "tappers" many times, but always thought "bangers" would be better. Some are very noticeable, and sound like they're coming apart.

 

[zeeprogrammer]

It's neat.
I'm going to have to organize my list of projects too.

 

[Lorenz]

Looks beautifull,

but, does it not run better when you make the connection pipes shorter?
that water, can you explane what that does?
Why does the pump pumps water?

I have never seen that.

greetings.

 

[Noitoen]

I don't think it's a water pump. The water is there to cool the cold side of the engine.

 

[mklotz]

that water, can you explane what that does?
Why does the pump pumps water?

I have never seen that.

Lorenz,

The cold side of the displacer chamber is encased in a sealed container. The pump pumps water into the space between the displacer chamber and the sealed container. It's the same principle as the water jacket on an automobile engine. The water carries away heat from the displacer chamber to keep it cool.

The water is pumped from the bottom of the water reservoir where the cooler water will settle while the warmer water coming from the water jacket is dripped to the top of the reservoir.

In an engine meant to run for a long time, the water reservoir would be replaced with a radiator (as in an auto engine) to dump the heat to the atmosphere. Since this engine is only run for short periods of time, a simple water reservoir can be used in lieu of the radiator, depending on the large thermal mass of the water for short term cooling.

 

[ksouers]

Marv,
Is the top of the container removable? I was thinking an ice cube or two would help make an even greater temperature differential.

Or perhaps even some dry ice and alcohol and make it really cold!

 

[mklotz]

Yes, I've put ice in the reservoir at shows.

There are many approaches to dumping the heat but I'm not strongly motivated to do anything complicated because the engine is never run for long periods.